Superstructure and methods for manufacturing the same

ABSTRACT

A method ( 30 ) for manufacturing a dental superstructure or part thereof is provided. The method comprises the steps of (i) making ( 31 ) a dental imprint from the mouth of a subject; (ii) mounting ( 32 ) an analog in the imprint to obtain a working model; (iii) attaching ( 33 ) a screw channel directing device ( 10, 20 ), comprising a screw channel part ( 11, 21 ) and an implant cooperating part ( 12, 22 ), said screw channel part ( 11, 21 ) being tiltable in relation to the implant cooperating part ( 12, 22 ), to the working model; (iv) tilting ( 34 ) the screw channel part ( 11, 21 ) in relation to the implant cooperating part ( 12, 22 ) into a desired angle; (v) shaping a mold creating a master superstructure or part thereof onto the screw channel directing device ( 10, 20 ); (vi) forming ( 37 ) a mold based on the master superstructure or part thereof; and (vii) casting ( 38 ) or CAD/CAM shaping of the dental superstructure or part thereof. Embodiments of screw channel directing devices are also provided.

This application is a National Stage Application of PCT/EP2012/059152,filed 16 May 2012, which claims benefit of Serial No. 1150443-8, filed16 May 2011 in Sweden and which applications are incorporated herein byreference. To the extent appropriate, a claim of priority is made toeach of the above disclosed applications.

TECHNICAL FIELD

The present invention relates to methods for manufacturing of dentalsuperstructures for attachment to dental implants or dental abutments.More specifically, the present invention relates to methods formanufacturing such dental superstructures through casting or CAD/CAMmilling/sintering with angled screw channels for screw retaining saidsuperstructure to the dental implant or dental abutment.

BACKGROUND

When securing a dental prosthesis to the jaw of a patient, it iscommonly known to attach a superstructure to osseointegrated dentalimplants. However, since the position and angle of the dental implantsvary greatly from patient to patient, the use of angled distances iscommon. These distances are placed upon the dental implant, and thesuperstructure is then most often cemented to the distances, since it isdifficult to screw retain the superstructure to such distances. However,when using separate distances, these will inevitably extend—at least tosome extent—in the axial direction of the dental implant. It is thenoften very difficult or even impossible to apply the superstructure onsuch distances, since the application of the superstructure calls for asubstantially parallel arrangement of the distances. Also, the mountingprocess when using such distances is very complicated and cumbersome,since a vast number of different distances must be tested on theimplants, to find the needed match. Also, interfaces between thedistances and the superstructure are hygienically bad.

In order to model the desired position of the screw channel mouth inscrew retained superstructures, it is known to position acrylic tubes ona model of the jaw of a subject. The model shows the position of theosseointegrated dental implants, and the acrylic tubes are placed atthese positions and bent to the desired curvature before a mould isformed, based on the bent acrylic tubes. Subsequently, separate seatsupport cylinders are planarized together with the castedsuperstructure, whereafter the separate screw member seat supportcylinders are welded onto the casted superstructure.

However, it may be hard to bend the acrylic tubes correctly. Bending thetubes to the desired curvature is tedious and the tubes may flex afterbending, which may result in a mould with erroneous angles. Furthermore,it is only possible to obtain bent screw channels, following acurvature, whereby the angle between the central axis of the mouth ofthe attached screw seat and the central axis of the screw channel mouthis limited to angles less than 17 degrees. Also, the manufacturingprocedure is quite cumbersome, including several separate manufacturingsteps, such as casting, planarization, fitting, welding etc.

Thus, there is a need for a new method and device, allowing for improvedconstruction of angled distances.

SUMMARY OF THE INVENTION

Accordingly, the present invention preferably seeks to mitigate,alleviate or eliminate one or more of the above-identified deficienciesin the art and disadvantages singly or in any combination and solves atleast the above mentioned problems by providing a method formanufacturing a dental superstructure or part thereof, comprising thesteps of (i) making a dental imprint from the mouth of a subject; (ii)mounting an analog in the imprint to obtain a working model; (iii)attaching a screw channel directing device, comprising a screw channelpart and an implant cooperating part, said screw channel part beingtiltable in relation to the implant cooperating part, to the workingmodel; (iv) tilting the screw channel part in relation to the implantcooperating part into a desired angle; (v) shaping a mold creating amaster superstructure or part thereof onto the screw channel directingdevice; (vi) forming a mold based on the master superstructure or partthereof; and (vii) casting or CAD/CAM shaping of the dentalsuperstructure or part thereof;

a screw channel directing device, comprising a screw channel part and animplant cooperating part, said screw channel part comprising a screwchannel mouth in the distal end, and a screw member seat with a screwhole in the proximal end, wherein the proximal end of the screw channelpart is bowl shaped, such that the inner bottom surface has a concaveshape and its outer bottom surface has a convex shape, and wherein thescrew hole of the screw member seat is a long hole, and wherein saidimplant cooperating part is collar-shaped with an implant seat at itsproximal end, and a distal concave screw channel part seat, wherein thescrew channel part seat has a radius corresponding to the radius of theouter bottom surface of the screw channel part to form a ball joint,such that the central axis of the screw channel part may betilted/angled in relation to a central axis of the implant cooperatingpart; and

a screw channel directing device, comprising a screw channel part and animplant cooperating part, said screw channel part comprising a screwchannel mouth in the distal end, and a screw member with a distalgripping portion in the proximal end, said screw member being arrangedin a screw member seat at the bottom proximal end of the screw channel,wherein said screw member has a screw member head in the proximal end,said screw member head having a head configuration in form of aperipheral contour, adapted for cooperation with the implant cooperatingpart, wherein said screw member part comprises a concave interactionsurface for cooperation with a convex interaction surface on the implantcooperating part to form a ball joint, said screw member head having aslanting distal contact surface for cooperation with a contact surfaceon the implant cooperating part when the central axis of the screwchannel part is angled in relation to the central axis of the implantcooperating part.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which the inventionis capable of will be apparent and elucidated from the followingdescription of embodiments of the present invention, reference beingmade to the accompanying drawings, in which

FIG. 1 is a schematic cross-section of a tiltable screw channeldirecting device according to an embodiment; and

FIG. 2 is a schematic cross-section of a tiltable screw channeldirecting device according to another embodiment

FIG. 3 is a flowchart showing the steps of a method according to anembodiment; and

FIG. 4 is a flowchart showing the steps of a method according to anotherembodiment

DESCRIPTION OF EMBODIMENTS

Several embodiments of the present invention will be described in moredetail below with reference to the accompanying drawings in order forthose skilled in the art to be able to carry out the invention. Theinvention may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the invention to thoseskilled in the art. The embodiments do not limit the invention, but theinvention is only limited by the appended patent claims. Furthermore,the terminology used in the detailed description of the particularembodiments illustrated in the accompanying drawings is not intended tobe limiting of the invention.

Embodiments of the present invention relate to methods for producing acast dental superstructure, with improved angling possibilities andfacilitated manufacturing. The embodiments are realized by the aid of anangled distance in form of a screw channel directing device. The screwchannel directing device is used to obtain an angled screw channel inthe cast dental superstructure, whereby the angle between a central axisof a screw channel mouth and the central axis of the dental implant,osseointegrated in the jaw of a subject, may be increased, in comparisonwith cast superstructures with bent screw channels according to theprior art.

In an embodiment according to FIG. 1, a screw channel directing device10 is provided. The screw channel directing device 10 comprises a screwchannel part 11 and an implant cooperating part 12. The screw channelpart 11 comprises a screw channel mouth 13 in the distal end. The screwchannel part 11 also comprises a screw member seat 14 in the proximalend of the screw channel. The screw channel part 11 may be substantiallycylindrical with a central axis and a distal screw channel mouth end anda proximal screw member seat end. The central axis of the screw channelruns through the center of the screw channel mouth and through the mouthof the screw member seat 14. Preferably, the screw channel part 11 has acircular cross-section along the central axis of the screw channel. Thecircular cross-section may have a first diameter at the proximal end,and then increasing when moving along the longitudinal central axis ofthe screw channel towards its proximal end. In the proximal end, thescrew channel part 11 is bowl shaped, such that the inner bottom surfacehas a concave shape and its outer bottom surface 15, i.e. its proximalend, has a convex shape. The screw hole of the screw member seat 14 is along hole. A long hole is a stretched hole.

The implant cooperating part 12 is a collar comprising an implant seat16 at its proximal end, and a distal concave screw channel part seat 17.The screw channel part seat 17 has a radius corresponding to the radiusof the outer proximal end of the screw channel part 11, such that thescrew channel part 11 may be tilted angled in relation to the implantonto which the implant cooperating part 12 is arranged. The implant seat16 at the proximal end of the implant cooperating part 12 may beadjusted according to different implant systems available on the market,such that different implant cooperating parts may be used depending onwhich dental implant is inserted into the jaw bone of the patient.

When angling/tilting the screw channel part 11 on the implantcooperating part 12, a screw member 18 is inserted into the screwchannel of the screw channel part 11. Then the screw channel part 11 isloosely screwed into the dental implant through the lumen of the collarof the implant cooperating part 12, with the implant cooperating part 12distally of the implant but proximally of the screw channel part 11. Inthis position the screw channel part 11 may be angled/tilted intodesired position, by rotating the screw channel part 11 such that thelong hole gets into the desired position, i.e. in which the long hole isin the direction of the plane in which the screw channel part 11 iswished to be angled/tilted. The long hole of the screw member part 11may extend from the central axis towards the perimeter of the screwchannel part 11, as can be seen in FIG. 1B, which shows the screwchannel part 11 from the end which is intended to be positioned towardsthe working model. Thus, by sliding the screw channel part 11 in theconcave screw channel part seat 17 of the implant cooperating part 12along the extension of the long hole, when the implant cooperating part12 is attached to the model, via the implant analog, but not yet fullysecured, it is possible to tilt the hollow screw channel part 11 inrelation to the model, as can be seen in FIG. 1C.

In FIG. 2 another embodiment of a screw channel directing device isillustrated. In this embodiment the screw channel directing device 20comprises a screw channel part 21 and an implant cooperating part 22.The screw channel part 21 comprises a screw channel mouth 23 in thedistal end. The screw channel part 21 may be substantially cylindricalalong the extension of the screw channel, with a central axis and adistal screw channel mouth end and a proximal screw hole 24 with aninternal thread. The central axis of the screw channel is also thecentral axis of the screw channel mouth 23. Preferably, the screwchannel part 21 has a circular cross-section along the central axis ofthe screw channel.

In the proximal end of the screw channel of the screw channel part 21 ascrew member 25 is arranged. The screw member 25 extends through a screwmember seat at the bottom proximal end of the screw channel of the screwchannel part 21. The screw member 25 has a distal gripping portion 26adapted for cooperation with a screwing device, such as screw driver,wrench, spanner, etc. In the proximal end the screw member has a screwmember head 27. The screw member head 27 has head configuration in formof a peripheral contour, adapted for cooperation with the implantcooperating part 22 for screwing the implant cooperating part 22 intothe dental implant or implant analog, in accordance with below.Proximally of the screw member seat, the screw channel part 21 comprisesa concave interaction surface 28, for cooperation with the implantcooperating part 22.

In one embodiment, the screw member 25 has a right handed threaded partproximally of the gripping portion. This right handed threaded part maybe used to screw the screw member distally, by rotating the distalgripping portion in a right handed way, to secure the implantcooperating part 22 to the dental implant or implant analog.

In another embodiment, the screw member 25 comprises two thread portionsproximally of the distal gripping portion, in form of a distal threadportion and a proximal thread portion. Preferably, the distal screwportion is right-handed threaded while the proximal thread portion isleft-handed threaded. The screw member head 27 is then attached to thescrew member 25 via the proximal left-handed thread. When the screwmember head 27 is connected to the screw member 25 via a left-handedthread, the screw member head 27 may be screwingly separated from thescrew member 25, by rotating the gripping portion 26 in a left-handedway, once the screw member head is in a bottom position, i.e. either inbottom cooperation with the implant cooperation part 22 or when theimplant cooperating part 22 and the screw channel part 21 are pressedagainst each other, in accordance with below. This brings about thetechnical effects of enabling separation of the screw channel part 21and the implant cooperating part 22 when the screw channel part 21 issecured, such as welded, cast, or solded to the superstructure.

The implant cooperating part 22 has a proximal pin 28 with a threadedpart, with an external thread, suitable for securing the implantcooperating part 22 to a dental implant. A dental implant seatcooperating part may be arranged at the distal end of the pin 28, byarranging a flange 29 circumferentially of the implant seat, said flangehaving an inner contour corresponding to the dental implant seat at thedistal end of the dental implant. In accordance with above, differentimplant systems available on the market with differing implant seats,such that different implant cooperating parts 22 may be used dependingon which dental implant is inserted into the jaw bone of the patient.

The implant cooperating part 22 has an inner gripping cavity in itsdistal end, said cavity corresponding in shape to the proximal screwmember head of the screw member, such that the implant cooperating part22 may be screwingly secured to the dental implant by screwing theimplant cooperating part 22 into the dental implant with by rotating thescrew member when the screw member head is in engaged cooperation withthe distal inner gripping cavity of the implant cooperating part 22.

The implant cooperating part 22 has an outer convex shape, forming aconvex interaction surface for cooperation with the screw channel part21. The convex interaction surface is adapted to cooperate with theproximal concave proximal concave interaction surface of the screwchannel part 21, such that the cooperation works as a ball joint,whereby the screw channel part 21 may be angled/tilted into the desiredposition.

The screw member head 27 is adapted to be inserted into the bottom ofthe cavity with the corresponding shape in the distal end of the implantcooperating part 22 when the screw channel part 21 is arranged inperfect alignment with the implant cooperating part 22, i.e. when thecentral axis of the screw channel part 21 coincides with the centralaxis of the implant cooperating part. When then the central axis of thescrew channel part 21 is angled in relation to the central axis of theimplant cooperating part 22, the screw member head 27 can no longer beseparated from the implant cooperating part 22. This can be accomplishedby having a slanting contact surface on the distal end of the screwmember head 27, such as for example semi-spherical or spherical shape,and a corresponding negative slanting surface in the cavity of theimplant cooperating part 22. In this way the screw member head 27 may bescrewed distally to secure the screw channel part 21 to the implantcooperating part 22.

In an embodiment, according to the flow chart in FIG. 3, a method 30 forproducing a cast dental superstructure is provided. The cast dentalsuperstructure is manufactured by the aid of an angled distance, bymeans of screw channel directing devices according to above. The screwchannel directing device is used to obtain an angled screw channel inthe cast dental superstructure, whereby the angle between a central axisof a screw channel mouth and the central axis of the dental implant,osseointegrated in the jaw of a subject, may be increased, in comparisonwith cast superstructures with bent screw channels according to theprior art. Thus, the screw channel of the screw channel directing devicehas substantially one central axis extending through the hollow cylinderscrew channel.

The screw channel directing device is tiltable due to a screw channelpart and an implant cooperating part which are described above.

In one embodiment thescrew channel part may be meltable in the castingtemperature, such that the screw channel part disintegrates duringcasting. In these instances the screw channel part may be made of aplastics or wax.

A dental imprint is made 31 from a subject according to methods known toa person skilled in the art. From the imprint a model of the subjectsdental situation is manufactured, according to methods known to theperson skilled in the art. In the obtained model of the subjects dentalsituation an implant analog is mounted 32.

Then, a screw channel directing device, according to below, is attached33 on the analog in the working model, with a laboratory screw. Theangle of the screw channel directing device is adjusted by tilting 34the screw channel part in relation to an implant cooperation part,comprised in the screw channel directing device. Then the laboratoryscrew is fastened to finally secure 35 the screw channel part of thescrew channel directing device to the working model in a desired angle.

This is advantageous, since it is possible to achieve angles larger than17 degrees, such as between 18 and 25, which is desirable since itallows for greater freedom in screw channel mouth placement on thesuperstructure. The angled screw channel, in contrast to the bent screwchannel according to prior art cast superstructures, also improvesaccess to the screw channel.

On top of the distance model, a superstructure master is made 36 fromwax or another meltable material. Thus, a superstructure master has beenobtained with an angled screw channel, wherein the angle has beenoptimally adapted in relation to the dental situation of the subject.

Thereafter, the master superstructure is dissembled by removing thelaboratory screw, if the screw channel directing device according toFIG. 1 is used, or loosening the threaded pin of the implant cooperatingpart 22 from the implant analog, if the screw channel directing deviceaccording to FIG. 2 is used. The master superstructure may then beseparated from the screw channel directing device by gently extractingthe screw channel directing devices from the master superstructure.

It is also possible to leave the screw channel directing device in themaster supertstructure.

In yet another embodiment, the master superstructure is scanned whenbeing positioned on the screw channel directing device 10, 20, forsubsequent CAD/CAM shaping, such as milling and sintering.

Then, the master superstructure is embedded in a cuvette with anembedding paste, specific for the material which ultimately will be usedto cast the distance, which is appreciated by a person skilled in theart.

The cavity obtained when extracting the screw channel directing deviceor the screw channel of the screw channel directing device is alsofilled with embedding paste. In those instances in which the screwchannel part of the screw channel directing device is of a material thatmelts during the casting procedure, in accordance with above, the moltin the subsequent casting will replace the screw channel part.

The cuvette is pre-heated according to the instructions specific for theembedding paste, which will make both the master superstructure andscrew channel directing device melt, in those instances a screw channeldirecting device is made of a material that melts during thispreheating, and the embedding paste hardens, forming 37 a mould.

Since the cavity of the screw channel directing device was also filledwith embedding paste, the mold represents the geometrical inverse of atubular, angular geometrical figure, i.e. the desired shape of thesuperstructure with angled screw channel.

The superstructure with angled screw channel is then cast 38 in a metalof choice, such as Titanium or Cobalt/Chromium alloy well known to aperson skilled in the art, according to the recommendations of themanufacturer of the material. After cooling, the cast superstructurewith angled screw channel may be blasted to create a smooth surface,preferably with aluminum oxide particles with a size between 110 and 250μm.

Optionally, the metal surfaces, which are intended to interact with ananalog/fixture, can be adjusted with a reamer. The other surfaces may beadjusted by means of a hard metal cutter.

The superstructure with angled screw channel is then ready to be fittedto the subject. The dental facing of the superstructure may be addedaccording to methods known to a person skilled in the art.

In another embodiment according to FIG. 4, a method 40 for producing asuperstructure with angled screw channel, by means of a screw channeldirecting device with oversized screw channel part is provided.

The screw channel directing device is tiltable due to a screw channelpart and an implant cooperating part, according to above.

The oversized screw channel part is larger than a subsequently usedscrew channel part, for reasons which will be apparent below.

The first steps of the method 40 are analogous to the previouslydescribed method 30.

A dental imprint is made 31 from a subject according to methods known toa person skilled in the art. An implant analog is mounted 32 in theimprint and a working model is made from plaster. An oversized screwchannel part is attached 33 on the working model by means of the implantcooperation part, with a laboratory screw.

The angle of the screw channel directing device is adjusted by tilting34 the screw channel part in relation to the implant cooperation partbefore the laboratory screw is fastened to finally secure 35 thetiltable, oversized distance model part to the working model, in adesired angle.

Optionally, the distance model is wax isolated to create a smoothsurface.

On top of the distance model, a master superstructure is made 36 from ameltable material, such as the plastic or wax as described above.

Optionally, a pre-casting is made.

The master superstructure is removed 41 from the oversized screw channelpart in an occlusional direction, after the master superstructure hasbeen detached from the implant analog(s).

The master superstructure is then embedded in a cuvette with anembedding paste, specific for the material which ultimately will be usedto cast the distance as is appreciated by a person skilled in the art.

The cuvette is pre-heated according to the instructions specific for theembedding paste, which will make the construct melt and the embeddingpaste harden, forming 37 a mould.

A superstructure is cast 38 in the mould with the metal of choice, suchas Titanium or Cobalt/Chromium alloy well known to a person skilled inthe art, according to the recommendations of the manufacturer. The castsuperstructure with angled screw channel is blasted to create a smoothsurface, preferably with aluminum oxide particles with a size between110 and 250 μm.

Optionally, the metal surfaces which are intended to interact with ananalog/fixture can be adjusted with a reamer. The other surfaces may beadjusted by means of a hard metal cutter.

A screw channel directing device 11, 21 is then inserted into thecavities formed by the oversized screw channel parts. The size of thescrew channel directing device 11, 21 is thus adapted to fit in theformed/cast cavity. The superstructure is then fastened to a workingmodel by laboratory screw(s).

The screw channel directing device are then fixed to the mastersuperstructure 42, such as welded, glued or soldered, together. This maybe done by first welding/gluing/soldering the screw channel directingdevice to the cast superstructure occlusionally and then at the positionof the implant cooperating part, thus forming a superstructure withangled screw channel(s).

Next, the screw channel directing device is cut 43 to fit with the castsuperstructure, so that no part extends outside the edges of thesuperstructure occlusally. The superstructure is then ready to be fittedto the subject. The dental facing of the superstructure may be addedaccording to methods known to a person skilled in the art.

The screw channel part 11, 21 may be made of a material that meltsduring production of the angled distance which the model is designed toprecede. Examples of meltable materials are plastic or wax.

The screw channel part 11, 21 of the screw channel directing device 10,20 may alternately be made from a metal, such as Titanium or aCobalt/Chromium alloy.

Although the present invention has been described above with referenceto specific embodiments, it is not intended to be limited to thespecific form set forth herein. Rather, the invention is limited only bythe accompanying claims and, other embodiments than the specific aboveare equally possible within the scope of these appended claims.

In the claims, the term “comprises/comprising” does not exclude thepresence of other elements or steps. Furthermore, although individuallylisted, a plurality of means, elements or method steps may beimplemented by e.g. a single unit or processor. Additionally, althoughindividual features may be included in different claims, these maypossibly advantageously be combined, and the inclusion in differentclaims does not imply that a combination of features is not feasibleand/or advantageous. In addition, singular references do not exclude aplurality. The terms “a”, “an”, “first”, “second” etc do not preclude aplurality. Reference signs in the claims are provided merely as aclarifying example and shall not be construed as limiting the scope ofthe claims in any way.

The invention claimed is:
 1. A method for manufacturing a dentalsuperstructure or part thereof, comprising the steps of (i) making adental imprint from the mouth of a subject; (ii) mounting an analog inthe imprint to obtain a working model; (iii) attaching a screw channeldirecting device, comprising a screw channel part and an implantcooperating part, said screw channel part being tiltable in relation tothe implant cooperating part, to the working model; (iv) tilting thescrew channel part in relation to the implant cooperating part into adesired angle; (v) shaping a mold creating a master superstructure orpart thereof onto the screw channel directing device; (vi) forming amold based on the master superstructure or part thereof; and (vii)casting or CAD/CAM shaping of the dental superstructure or part thereof.2. The method according to claim 1, wherein step (vii) is casting, andfurther comprising the step of (viii) removing the screw channeldirecting device from the master superstructure between step (v) andstep (vi); (ix) inserting a screw channel directing device,corresponding to the shape of the cavity formed by the screw channeldirecting device in step (v); and (x) attaching the screw channeldirecting device inserted in step (ix) by welding, gluing, or soldering.3. The method according to claim 1, wherein screw channel directingdevice or the screw channel part thereof is melted during step (vi) or(vii).
 4. The method according to claim 1, wherein screw channeldirecting device or the screw channel part thereof is a metal screwchannel directing device or metal screw channel part, which is adheredto the superstructure during step (vii).